>>> linalg.inv(2) Traceback (most recent call last): File "<stdin>", line 1, in ? File "/usr/lib64/python2.4/site-packages/scipy/linalg/basic.py", line 183, in inv raise ValueError, 'expected square matrix' ValueError: expected square matrix >>> linalg.inv(mat(2)) array([[ 0.5]]) Is this behaviour wanted ? Nils